TABLE I.

Comparison of “conventional” methods for mechanobiology. Viscoelastic property signifies the quantity typically extracted from experiments although other rheological functions can also be calculated. Force range for all techniques except FRET probes shows the force that the probe is capable of exerting but for FRET is the measurement range. Dynamic time scale indicates the typical time scale of the relaxation process that is probed.

Technique	Main viscoelastic property	Force range	Dynamic time scale	Linear dimension of the probed region	Meas. through-put (cell/h)	Reference
AFM	Young modulus Y = E(ω → 0)	10 pN–10 μN	ms–s	10 nm–5 μm	5–10	2 and 96
Parallel plate rheology	Elastic modulus E(ω)	10 pN–10 μN	ms–s	Whole cell	5–10	2
Rotating plate rheology	Shear modulus G(ω)	Limited by the adhesive properties of cells	ms–s	Whole cell	<106 (5–6 h needed to prepare cells)	2 and 97
Micropipete aspiration	Stretch modulus of envelope, strength of cell-to-cell and cell-to-substrate attachments	0.1 nN–1 μN	ms–min	>1 μm	5–10	20
Magnetic tweezers	Shear modulus G(ω)	0.1–100 pN	ms–min	1–10 μm	1000	2, 21, 98 and 99
Particle tracking rheology	Diffusion coefficient →G(ω)	N/A	ms–h	0.01–1 μm	10–100	2 and 22
FRET probes	Force, stress	1–100 pN	ms–min	1 nm to whole cell	10–100	24
Brillouin scattering	Spatial distribution of longitudinal modulus M(x, y)	N/A	ns	>250 nm	10–100	25 and 26
Optical stretchers	Creep function J(t)	<100 pN	ms–s	Whole cell	100	2 and 27
Laser ablation	Creep function J(t)	N/A	ms–s	>250 nm	5–10	29